Insulating your tiny house

There are three different types of insulation I considered for my tiny house;

Spray foam – I thought this might be the best choice since it has a high R value and there would be no leaks (since it is sprayed in to all the nooks and crannies). The reason I ultimately decided against it is because this is not a DIY solution and thus likely much more expensive.

Fiberglass – I’ve worked with fiberglass before and it is fairly inexpensive and very easy to install. The problem is it doesn’t have the highest R value (~ 3.4 per inch).

Styrofoam Boards supplemented with spray foam – This is a little more expensive than fiberglass (I’m not sure exactly what the comparison is) but has a much higher R value of 5 per inch. This was my choice because I thought it was the next best thing to pure spray foam and it was something I could do myself.

After working with the Styrofoam boards I think my decision might have been flawed, and in hindsight would have chosen differently. The first and most important reason is that while the R value of the Styrofoam is much higher per inch, the boards that I am using are 2 inches thick, thus giving me an effective R value of 10. If I were to use fiberglass, I would fill the entire wall cavity and thus have an effective R value of 12. Couple that with the ease/speed of installation (the boards are a huge pain and mess to work with) and the lower cost I think fiberglass would be the way to go for warmer climates (my TH is headed to Florida). For colder climates I think I would spring for the spray foam insulation.

This is something that needs to be done right the first time since it isn’t easy to change out. I would love to hear any opinions.

Fun fact: While researching R values I read that 1 inch of insulation is equivalent to 30 inches of concrete!

UPDATE: I have since worked with the styrofoam more and experimented with different cutting tools (circular and hand saw) and no longer find it as difficult to work with. I also got a better tool (Hilti) to inject the foam into the cracks. In addition, if I had used 3″ foam my R value concerns would be alleviated as well.

(lc:0, sc:0, lt:11, st:84)

6 thoughts on “Insulating your tiny house

  1. dlouche said:

    Thanks for the tip. Without a lot of research it looks like it might be about $1500 for a structure the size of my house (which would be about 3 times what I paid for the foamular and great stuff). Since it’s that much to do it yourself I’m really curious what someone would charge to do it.

    I will continue to look into it now that you’ve sparked my interest.

    Thanks again

  2. Penny said:

    The other tiny homes that I’ve seen blogs on have put in the first layer of insulation, then the wiring and plumbing, and then they’ve added another layer of insulation; increasing the overall R value.

    However, if you didn’t like putting in the first layer I’m pretty sure you won’t like putting in the second. The thing to remember about using DIY spray foam is that you need to do all the wiring and plumbing first.

    • dlouche said:

      The second layer probably wouldn’t be too bad to install seeing as how it would only be 1″ boards and easy to cut, and the big gaps would already be filled with foam. That might be a good option for me on this build.

      In the future, assuming I can get a better deal that $1500, I would probably go 100% spray foam.

      Can you share a link to one of the blogs you are referring too. I follow quite a few but don’t remember any that did the insulation in two layers

      Thanks!

  3. Claudia said:

    I just discovered your blog — which is awesome, thank you so much for sharing your experiences! — so I know you’re already finished with your mom’s house but you mentioned wanting to build another one so I thought it was worth mentioning that these Sing Honeycomb panels the Little House on a Trailer guy uses.

    More info can be found at http://www.superhoneycomb.com

    • Dan Louche said:

      Hey Claudia,

      Welcome! I’ve seen the sing panels before. I think they are a neat idea I just didn’t consider them because I wanted to be able to get most of my materials locally. I don’t know how much it would cost but I don’t think it would be cheap to ship 4′ x 8′ panels (but maybe not)

      Thanks for the info

      Dan

      • Claudia said:

        Yes, it’s too bad that you can’t pick these up at the local hardware store. The main appeal for me is that they’re light and easy to install.

        I’m not sure how much it would cost to ship. The website isn’t all that informative, unfortunately. I live in BC, so I hadn’t really thought about shipping costs since I could easily drive down to Washington to pick the panels up.

        That said, I think it’d be worthwhile to give them a phone call to see how much shipping costs would be. Ultimately, you’d be saving build time and — though this is only a consideration if you plan to move your tiny home often, which isn’t the case for most people — fuel since the resulting house would be lighter. If nothing else, the door is worth getting out of this material because of the high R-value. (Not an issue for your mother in Florida, but it sounds like it gets very cold in your area!)

Leave a Reply

Your email address will not be published. Required fields are marked *